Locomotive control of a wearable lower exoskeleton for walking enhancement

This article presents a wearable lower extremity exoskeleton (LEE) designed to augment the ability of a human to walk while carrying payloads. The ultimate goal of the current research is to design and control a wearable power-assisted system that integrates a human's intellect as the control command. The system in this work consists of an inner exoskeleton and an outer exoskeleton. The inner system measures the movements of the human and controls the outer system, which follows the human movements and supports the payload. A special foot-unit was designed to measure the zero moment points (ZMPs) of the human and the exoskeleton simultaneously. Using the measured human ZMP as the reference, the exoskeleton's ZMP is controlled by trunk compensation to achieve stable walking. A COTS program, xPC Target, together with toolboxes from MATLAB, were used as a real-time operating system and integrated development environment, and real-time locomotion control of the exoskeleton was successfully implemented in this environment. Finally, some walking experimental results, by virtue of the ZMP control for the inner and outer exoskeletons, show that the stable walking can be achieved.